US5463302A - Slip compensation method in a squirrel cage induction motor - Google Patents

Slip compensation method in a squirrel cage induction motor Download PDF

Info

Publication number
US5463302A
US5463302A US08/303,756 US30375694A US5463302A US 5463302 A US5463302 A US 5463302A US 30375694 A US30375694 A US 30375694A US 5463302 A US5463302 A US 5463302A
Authority
US
United States
Prior art keywords
motor
frequency
compensation
rated
slip
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US08/303,756
Other languages
English (en)
Inventor
Torma
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ABB Industry Oy
Original Assignee
ABB Industry Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ABB Industry Oy filed Critical ABB Industry Oy
Assigned to ABB INDUSTRY OY reassignment ABB INDUSTRY OY ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: TORMA, JUHA
Application granted granted Critical
Publication of US5463302A publication Critical patent/US5463302A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
    • H02P23/08—Controlling based on slip frequency, e.g. adding slip frequency and speed proportional frequency

Definitions

  • This invention relates to a method for slip compensation in a squirrel cage induction motor when the motor is fed by an inverter without feedback at a supply frequency less than 20% of the rated supply frequency of the motor after the motor has first been fed at a frequency more than 50% of the rated frequency for a period of time at least equal to a mechanical time constant of a combination formed by the motor and a load device, wherein a term proportional to the torque of the motor is determined and added to the set value of the rotation speed to effect slip compensation.
  • Techniques of the type described above are used for the compensation of the slip of squirrel cage induction motors particularly in lifts, conveyors, cranes and trains, in which the motor is normally driven at a greater frequency typically more than 50% of the rated frequency of the motor, but which are driven at a low drift speed before the motor is switched off, whereby the supply frequency of the motor is typically less than 20% of the rated frequency of the motor. In this way, stopping can be performed smoothly.
  • the system does not comprise position feedback or speed feedback e.g. from a tachometer measuring the rotation speed of the motor, speed variation caused by the slip of the motor is to be compensated for electrically.
  • Such a system can be e.g. a positioning drive without feedback information from the motor shaft, where a short distance is driven at a low approach speed which is to be load-independent before positioning in order to improve accuracy.
  • n the set value of the rotation speed (r/min)
  • k a constant dependent on the degree of magnetization of the machine
  • Equation (1) The term kT in Equation (1) is obtained by an estimated air-gap power Pa obtained by a power measured from an intermediate circuit between a rectifier and an inverter as follows:
  • Ps the dissipation power of the stator of the motor.
  • the torque of the motor in turn is obtained from the air-gap power Pa as follows:
  • Ws the angular frequency of the stator.
  • the accuracy of the above-described method decreases with decreasing frequency, as the proportion of the dissipation powers Pinv and Ps in the measured power of the intermediate circuit increases with decreasing frequency when the load remains constant.
  • the frequency is 0, the entire power of the intermediate circuit is lost through losses as the air-gap power Pa of the machine is 0.
  • changes in the degree of magnetization caused by the voltage loss of the stator resistance alter the value of the constant k, thus deteriorating the accuracy of the term kT the more the lower the frequency is.
  • the inaccuracy caused by the above-described method in slip calculation with decreasing frequency results in variation in the approach speed with different loads.
  • the object of the method according to the invention is to provide a solution in which such approach speed variation is reduced significantly. This is achieved by a method according to the invention which is characterized in that the value of the compensation term is stored in a memory before transition from the frequency more than 50% of the rated frequency to a frequency less than 50% of the rated frequency, and the stored compensation term is used as such for slip compensation when the supply frequency of the motor is less than 20% of the rated frequency.
  • the accuracy of slip compensation is improved in such a way that the compensation value to be added to the rotation speed of the motor when driving at a low approach frequency (less than 20% of the rated frequency of the motor) is calculated at a higher constant frequency (more than 50% of the rated frequency of the motor), whereby the effect of dissipation powers on the calculation accuracy of the compensation value is insignificant.
  • the method according to the invention is based on the realization that in drives of the type described above the load is not able to change until the motor has been switched off completely. This is because one cannot leave a lift or a train before it has stopped, i.e., the load of the motor remains constant throughout the period of time when the motor is first driven at a higher rated frequency and then a lower drift speed is applied before stopping.
  • FIG. 1 shows a speed profile for positioning drive to which the method according to the invention is applicable.
  • FIG. 2 is a block diagram illustrating a device suitable for realizing the method according to the invention.
  • FIG. 1 shows a speed profile for positioning drive to which the method according to the invention can be applied.
  • the motor is started at a time 0, and its rotation speed is adjusted such that it is operated at a frequency at least about 50% of the rated frequency of the motor up to a time t 1 .
  • the time interval from 0 to t 1 should be at least equal to a mechanical time constant of a combination formed by the motor and a load device.
  • the motor is commanded to a frequency no more than 20% of the rated frequency of the motor.
  • the motor is driven at such a low speed up to a time t 2 , after which the motor is switched off.
  • a term kT to be added to the set value of the rotation speed of the motor is calculated at t 1 by Equations (1) to (3) presented above.
  • the term kT is used as such for slip compensation up to t 2 . This value stored in a memory is thus no more changed during the rest of the positioning drive.
  • FIG. 2 shows a block diagram illustrating generally a device suitable for realizing the method according to the invention.
  • a power obtained from a three-phase network is rectified e.g. by a diode bridge 3, whereafter the rectified voltage is filtered in a capacitor 4 and applied to an inverter 1, which in turn feeds a motor 2.
  • the inverter is controlled by a pulse-width modulator 5, which applies an electric stator frequency fs to the inverter as a frequency command. If the slip of the motor is not to be compensated for, this frequency is calculated merely from the set value of the rotation speed n of the motor.
  • the arrangement further comprises a slip compensation circuit 6, which measures a DC power Pdc from an intermediate circuit between the rectifier 3 and the inverter 1.
  • the slip calculation circuit 6 then calculates the torque T of the motor on the basis of the DC power, and multiplies it with an appropriate constant k. This gives a compensation term kT, which is added to the set value of the rotation speed n in an adder 7 so as to obtain a slip-compensated stator frequency fs in accordance with Equation 1.
  • the slip calculation circuit 6 shown in FIG. 2 stores, in the positioning drive illustrated in FIG.
  • the term kT in the memory at t 1 and applies only this value to the adder 7 when the value of the set rotation speed n requires that the motor be fed at a frequency less than 20% of the rated frequency of the motor. Accordingly, the compensation accuracy can be improved by calculating the compensation value kT used during drive at a low approach frequency at a high constant frequency, whereby the effect of dissipation powers on the calculation accuracy of the value is insignificant.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Ac Motors In General (AREA)
US08/303,756 1993-09-24 1994-09-09 Slip compensation method in a squirrel cage induction motor Expired - Lifetime US5463302A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI934200A FI94200C (fi) 1993-09-24 1993-09-24 Menetelmä oikosulkumoottorin jättämän kompensoimiseksi
FI934200 1993-09-24

Publications (1)

Publication Number Publication Date
US5463302A true US5463302A (en) 1995-10-31

Family

ID=8538657

Family Applications (1)

Application Number Title Priority Date Filing Date
US08/303,756 Expired - Lifetime US5463302A (en) 1993-09-24 1994-09-09 Slip compensation method in a squirrel cage induction motor

Country Status (5)

Country Link
US (1) US5463302A (fi)
JP (1) JPH07203697A (fi)
DE (1) DE4432700A1 (fi)
FI (1) FI94200C (fi)
GB (1) GB2282282B (fi)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004042457A2 (en) 2002-11-05 2004-05-21 Donnelly Corporation Electro-optic reflective element assembly
EP3624086A1 (en) 2007-01-25 2020-03-18 Magna Electronics Inc. Radar sensing system for vehicle

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5747963A (en) * 1996-09-23 1998-05-05 Motorola, Inc. Method for controlling an electric motor and electric apparatus

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4926105A (en) * 1987-02-13 1990-05-15 Mischenko Vladislav A Method of induction motor control and electric drive realizing this method
US5272429A (en) * 1990-10-01 1993-12-21 Wisconsin Alumni Research Foundation Air gap flux measurement using stator third harmonic voltage and uses

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1292769C (en) * 1986-11-12 1991-12-03 Errol E. Wallingford Three-phase pwm inverter with speed control and load compensation for aninduction motor
EP0423384B1 (de) * 1989-10-16 1993-07-28 Otis Elevator Company Steuerungsvorrichtung für Aufzuganlage ohne Geschwindigkeitsfühler
JPH0433584A (ja) * 1990-05-30 1992-02-04 Toshiba Corp すべり検出装置およびこれを用いた圧縮機の制御装置

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4926105A (en) * 1987-02-13 1990-05-15 Mischenko Vladislav A Method of induction motor control and electric drive realizing this method
US5272429A (en) * 1990-10-01 1993-12-21 Wisconsin Alumni Research Foundation Air gap flux measurement using stator third harmonic voltage and uses

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Power Electronics; Mohan et al.; 1989; pp. 311 311, 333 and 335, John Wiley & Sons, New York. *
Power Electronics; Mohan et al.; 1989; pp. 311-311, 333 and 335, John Wiley & Sons, New York.

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004042457A2 (en) 2002-11-05 2004-05-21 Donnelly Corporation Electro-optic reflective element assembly
EP3624086A1 (en) 2007-01-25 2020-03-18 Magna Electronics Inc. Radar sensing system for vehicle

Also Published As

Publication number Publication date
FI934200A0 (fi) 1993-09-24
JPH07203697A (ja) 1995-08-04
DE4432700A1 (de) 1995-03-30
FI94200B (fi) 1995-04-13
GB2282282A (en) 1995-03-29
GB2282282B (en) 1997-08-13
FI94200C (fi) 1995-07-25
GB9418552D0 (en) 1994-11-02

Similar Documents

Publication Publication Date Title
Kirschen et al. Optimal efficiency control of an induction motor drive
US7235947B2 (en) Synchronous motor control method and synchronous motor control system
US5739664A (en) Induction motor drive controller
US10126150B2 (en) Method and apparatus for estimating an angle offset of an angle sensor
JP3144640B2 (ja) 巻上げ用モータの制御方法とその装置
CA2159405C (en) Procedure for starting an elevator
US4815567A (en) Apparatus for controlling an A.C. powered elevator
US5463302A (en) Slip compensation method in a squirrel cage induction motor
JP3017788B2 (ja) 速度センサを持たないエレベータ装置用の制御装置
US20050046371A1 (en) Method and apparatus for controlling a brushless DC motor
KR101203911B1 (ko) 유도전동기의 제어방법, 제어장치, 제철 ?비철설비,철도차량, 권취기, 선박, 공작기계, 초지기설비 및반송설비
JP4698312B2 (ja) 電力変換装置
US4667777A (en) Control apparatus for A.C. elevator
KR101246485B1 (ko) 엘리베이터의 도어 제어 장치
US5384439A (en) Adaptive digital velocity control loop for a high performance elevator door system with low cost
JP3612953B2 (ja) 誘導電動機の制御装置
CA2327582A1 (en) Method and apparatus for indirectly measuring induction motor slip to establish speed control
JPH08208140A (ja) エレベータの制御装置
JP2001157479A (ja) 誘導電動機の制御装置
JP4568998B2 (ja) 誘導電動機の制御装置
JP2935583B2 (ja) エレベータ用インバータの速度制御装置
SU1394384A1 (ru) Способ управлени тиристорным электроприводом посто нного тока буровой лебедки
Paul et al. AC operated EOT crane control with variable voltage variable frequency drive
SU1432706A2 (ru) Устройство зависимого управлени полем двигател посто нного тока
FI91685B (fi) Menetelmä oikosulkumoottorin käämityksen lämpötilan määrittämiseksi

Legal Events

Date Code Title Description
AS Assignment

Owner name: ABB INDUSTRY OY

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TORMA, JUHA;REEL/FRAME:007401/0713

Effective date: 19940811

STCF Information on status: patent grant

Free format text: PATENTED CASE

FPAY Fee payment

Year of fee payment: 4

FEPP Fee payment procedure

Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

FPAY Fee payment

Year of fee payment: 8

FPAY Fee payment

Year of fee payment: 12